Channel letters are used to provide signage for buildings, shopping malls, and the like where it is desirable that the signage comprise illuminated letters or any other shapes that are easily seen, even at great distances, day or night. Each channel letter consists of an enclosure, usually a metal box, having a rear surface which is positioned against a raceway, or the wall of a building, on which the signage is mounted and a plurality of sides which define the figuration of a letter or number which make up a portion of the sign. A light source, such as a neon tube, is positioned within the walls of the enclosure and attached to the rear surface to provide illumination for the letter.
The light sources used in existing channel letters are neon bulbs requiring high voltage power with transformers built into the metal enclosures. To prevent injury to those servicing such channels letters many municipalities require that such letters be inspected to ensure that they are adequately sealed using standards set by Underwriters Laboratories.
It is expected that new technology will soon be available for the manufacturers of channel letters. Specifically, low voltage LED type light sources have been developed which provide a very long lasting bright light without requiring the high voltage and transformers needed for neon lighting. It is expected that channel letters employing the new technology will not be required to meet the standards set by Underwriters Laboratories.
In addition to the lighting, a channel letter also includes a planar, transparent lens, the outer shape of which corresponds to the figuration of the letter or any other shape defined by the sides of the enclosure. The lens of existing channel letters have a trim cap glued to the outer edges thereof which form a border to the lens. The trim cap also has a lip which, when assembled to the enclosure, is shaped to fit snugly around the forward ends of the walls thereof for retaining the lens to the enclosure and to maintain the water tight seal required by Underwriters Laboratories. Screws are threaded through the lips of the trim cap and into the walls to retain the lens across the forward opening of the enclosure.
The manufacture of the lens requires that a planar panel of transparent plastic be cut to the shape of the enclosure and that the trim cap be glued to the outer edges of the lens. The contours of the sides of many letters are curved and the process of shaping and gluing the trim cap around the edges of the lens is labor intensive. It is, therefore, expensive to manufacture existing lenses which fit across the forward ends of the enclosure of a channel letter.
It would be desirable to provide a channel letter having a lens which could be manufactured without incurring the labor intensive step of attaching a trim cap. It would also be desirable to provide a less expensive method of manufacturing and assembling a lens to the enclosure of a channel letter.
Briefly, the present invention is embodied in a channel letter. For the purposes of this description, a channel letter is defined as an eliminated contoured fixture in the shape of a letter of the alphabet, a numeral, an element of punctuation such as a comma, an exclamation point, or any other shape or form intended to constitute a portion of a sign.
The channel letter of the present invention has a rear surface for mounting against a raceway, a wall, or any other structure suitable for supporting the signage. The walls defining the figuration of the letter or shape to be depicted are made of sheet metal having a given thickness. A lighting element, such as a strip of LEDs according to the newly available technology or any other light source, is positioned against the rear surface of the enclosure to provide illumination therefore.
To retain the lens to the open front of the enclosure, a shoulder, preferably made of foam or rubber, is provided around the inner surface of the sides thereof where the shoulder defines a plane parallel to the outer ends of the sides but is recessed therefrom. A planar transparent lens having an outer edge which is in the shape of the letter and sized to fit within the sides of the enclosure is retained against the shoulder by a plurality of retaining clips which fit around the edge of the sheet metal walls.
In accordance with the present invention to retain the lens against the shoulder a plurality of retainer clips are spaced along the outer end of the walls of the enclosure. Each of the retainer clips consists of a unitary generally ridged body having a first leg and a second leg with the legs extending from an arched back. The legs are spaced from each other by a distance that is a little greater than the given thickness of the sheet metal of the walls. At least one semi-ridged/semi-flexible finger extends from the surface of one of the legs and into the space between the legs. In the preferred embodiment the finger is made from polyurethane and the body of the retainer clip is made from a transparent polycarbonate. Also, the fingers are not perpendicular to the side walls of the legs from which they project, but are at an angle with respect to the perpendicular with a component of the angle extending toward the arched back. The angled orientation of the fingers permit the clip to be easily fitted over the outer ends of the enclosure but resist removal of the retainer clip once it has been installed. A plurality of such retainer clips positioned around the outer edge of the walls thereby attaching the lens to the walls of the enclosure.
To provide lateral support to the enclosure, one or more cables may be provided to connect opposite walls of the enclosure.